Dorsal coloration variable; ground color may be cream, grey, red, or black. Dorsum may show a variable pattern of dark streaks and blotches. Head lacks tympanum, pupil is vertical, and a light streak may extend from tip of snout to above the eyes. Whitish-yellow venter, more yellow in femoral region. Males have a tail-like extension of the cloaca, and during breeding season show greatly enlarged forearms. Larvae have a distinctively large, round mouth, modified for suction, which they use to cling to streamside rocks (modified from Stebbins 1951).
Ascaphus is the only living representative of a basal lineage of anurans, and may retain some relatively primitive traits of early frogs (e.g. Ford and Cannatella 1992).
See another account at californiaherps.com.
Tailed frogs occur from northwestern California north to the Portland Canal and Nass River of British Columbia. This range is bordered by the Cascade Mountains to the east and the Pacific coast to the west. Several separate populations are also found in the Blue Mountains of southeastern Washington and northeastern Oregon as well as in the northern Rocky Mountains of northern Idaho and western Montana.
Biogeographic Regions: nearctic (Native )
Regularity: Regularly occurring
Type of Residency: Year-round
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Cascades and the Pacific Coast from southern British Columbia south to northwestern California (Nielson et al. 2001, Stebbins 2003).
Distribution and Habitat
From sea level to timberline, ranging along Pacific coast of North America from northern California to southern British Columbia. Also includes a disjuct distribution in northern Idaho and western Montana (Nussbaum et al 1983). Associated with cold, fast-moving streams with cobbled bottoms and emergent boulders (Bull and Carter 1996).
Since tailed frogs spend their life in association with fast-flowing streams, they have evolved some morphological adaptations that stand out from other frogs and toads. For example, the lungs are greatly reduced, presumably to control buoyancy, and the toe tips are hard and keratinized, to facilitate crawling among rocks on the stream bottom.
Juveniles and adults are small, typically ranging from 2.2 to 5.1 cm in snout-vent length. Overall, color is usually comparable to the tailed frog’s substrate and may vary from tan to chocolate brown or olive green. Regardless of the color, its skin has a characteristic rough feel. Moreover, the head is comparatively large and flattened with a light triangular-shaped mark generally present between the snout and eyes. The eyes themselves have visibly vertical pupils, and a dark stripe extends from the snout to the shoulder. Some more obvious adaptations to its streamside habitat include a slight webbing of the toes, with the outer hind toes also flattened. In addition, they lack tympani or ear membranes and, as a result, lacks the capacity to communicate acoustically, a likely adaptation to the steady sound of flowing water. Tailed frogs get their common name from another aquatic adaptation: males have a short, tail-like copulatory organ used during internal fertilization. Tailed frogs exhibit additional sexual dimorphism in that males are smaller than females, and they develop black, horny pads on the insides of their thighs during the mating season to aid gripping females during amplexus.
Tadpoles average little more than 11 mm after hatching, but may grow to 65 mm in length before metamorphosis. Initially, hatchlings have no color, but are instead identified according to the presence of a prominent yolk sac seen in the abdomen. However, tadpoles eventually take on a black to brownish-grey coloration of the body that is covered with black speckling. A white dot discernible on the tip of the tail and an obvious copper-colored bar between the eyes and snout are additional field marks for identification. Tailed frog tadpoles also have some adaptations to keep from being swept away by stream currents. The body is flattened ventrally and the tail is laterally compressed. Moreover, the mouth has evolved into an oral disc that is sucker-like, allowing for attachment to rocks. Eggs are unpigmented and are laid in a gelatinous string beneath a rock in shallow water.
Range length: 2.2 to 5.1 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike; female larger; sexes shaped differently
Length: 5 cm
Catalog Number: USNM 25979
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Year Collected: 1897
Locality: Humptulips, Grays Harbor, Washington, United States, North America
Central and Southern Cascades Forests Habitat
The Oregon slender salamander is endemic to the Central and Southern Cascades forests ecoregion. The Central and Southern Cascades forests span several physiographic provinces in Washington and Oregon, including the southern Cascades, the Western Cascades, and the High Cascades, all within the USA. This ecoregion extends from Snoqualmie Pass in Washington to slightly north of the California border. The region is characterized by accordant ridge crests separated by steep, deeply dissected valleys, strongly influenced by historic and recent volcanic events (e.g. Mount Saint Helens).
This ecoregion contains one of the highest levels of endemic amphibians (five of eleven ecoregion endemics are amphibians) of any ecoregion within its major habitat type. The threatened Northern spotted owl has been used as an indicator species in environmental impact assessments, since its range overlaps with 39 listed or proposed species (ten of which are late-seral associates) and 1116 total species associated with late-seral forests. Late-seral forests in general are of national and global importance because they provide some of the last refugia for dependent species, and perform vital ecological services, including sequestration of carbon, cleansing of atmospheric pollutants, and maintenance of hydrological regimes.
There are a number ofl amphibian taxa present in the Central and Southern Cascades ecoregion; the totality of these amphibian taxa are: the Rough-skinned newt (Taricha granulosa); the endemic and Vulnerable Shasta salamander (Hydromantes shastae); the endemic and Vulnerable Oregon slender salamander (Batrachoseps wrighti); the Endangered Dunn's salamander (Bolitoglossa dunni); the Northwestern salamander (Ambystoma gracile); the Near Threatened western toad (Anaxyrus boreas); the Vulnerable Oregon spotted frog (Rana pretiosa); the Near Threatened Cascades frog (Rana cascadae); Coastal tailed frog (Ascaphus truei); Near Threatened Larch Mountain salamander (Plethodon larselli); California newt (Taricha torosa); Pacific giant salamander (Dicamptodon ensatus); Cope's giant salamander (Dicamptodon copei); Monterey ensatina (Ensatina eschscholtzii); the Near Threatened Foothill yellow-legged frog (Rana boylii); Northern Red-legged frog (Rana aurora); Pacific chorus frog (Pseudacris regilla); Van Dyke's salamander (Plethodon vandykei), an endemic of the State of Washington, USA; Long-toed salamander (Ambystoma macrodactylum); and the Olympic torrent salamander (Rhyacotriton olympicus).
There are a moderate number of reptilian species present in the ecoregion, namely in total they are: Western pond turtle (Emys marmorata); Western fence lizard (Sceloporus occidentalis); Sharp-tailed snake (Contia tenuis); Ringed-neck snake (Diadophis punctatus); Rubber boa (Charina bottae); California mountain kingsnake (Lampropeltis zonata); Yellow-bellied racer (Coluber constrictor); Western rattlesnake (Crotalus viridis); Western gopher snake (Pituophis catenifer); Common garter snake (Thanophis sirtalis); Northwestern garter snake (Thamnophis ordinoides); Western skink (Megascops kennicottii); Southern alligator lizard (Elgaria multicarinata); and the Northern alligator lizard (Elgaria coerulea).
There is a considerable number of avifauna within the Central and Southern Cascades ecoregion; representative species being: Flammulated owl (Otus flammeolus); Western screech owl (Megascops kennicottii); White-tailed ptarmigan (Picoides albolarvatus); and White-headed woodpecker (Picoides albolarvatus).
There are a large number of mammalian taxa in the ecoregion, including: Bobcat (Lynx rufus); Wolverine (Gulo gulo); California ground squirrel (Spermophilus beecheyi); Yellow-bellied marmot (Marmota flaviventris); Ermine (Mustela erminea); Fog shrew (Sorex sonomae), an endemic mammal to the far western USA; Hoary marmot (Marmota caligata); Mountain beaver (Aplodontia rufa); and the Near Threatened red tree vole (Arborimus longicaudus); Yellow pine chipmunk (Tamias amoenus); and the American water shrew (Sorex palustris).
Puget Lowland Forests Habitat
Cope's giant salamander is found in the Puget lowland forests along with several other western North America ecoregions. The Puget lowland forests occupy a north-south topographic depression between the Olympic Peninsula and western slopes of the Cascade Mountains, extending from north of the Canadian border to the lower Columbia River along the Oregon border. The portion of this forest ecoregion within British Columbia includes the Fraser Valley lowlands, the coastal lowlands locally known as the Sunshine Coast and several of the Gulf Islands. This ecoregion is within the Nearctic Realm and classified as part of the Temperate Coniferous Forests biome.
The Puget lowland forests have a Mediterranean-like climate, with warm, dry summers, and mild wet winters. The mean annual temperature is 9°C, the mean summer temperature is 15°C, and the mean winter temperature is 3.5°C. Annual precipitation averages 800 to 900 millimeters (mm) but may be as great as 1530 mm. Only a small percentage of this precipitation falls as snow. However, annual rainfall on the San Juan Islands can be as low as 460 mm, due to rain-shadow effects caused by the Olympic Mountains. This local rain shadow effect results in some of the driest sites encountered in the region. Varied topography on these hilly islands results in a diverse assemblage of plant communities arranged along orographically defiined moisture gradients. Open grasslands with widely scattered trees dominate the exposed southern aspects of the islands, while moister dense forests occur on northern sheltered slopes characterized by Western red cedar (Thuja plicata), Grand fir (Abies grandis), and Sword fern (Polystichum munitum) communities.
There are only a small number of amphibian taxa in the Puget lowland forests, namely: Cope's giant salamander (Dicamptodon copei); Monterey ensatina (Ensatina eschscholtzii); Long-toed salamander (Ambystoma macrodactylum); Western redback salamander (Plethodon vehiculum); Northwestern salamander (Ambystoma gracile); Pacific chorus frog (Pseudacris regilla); Coastal giant salamander (Dicamptodon tenebrosus); Rough-skin newt (Taricha granulosa); the Vulnerable Spotted frog (Rana pretiosa); Tailed frog (Ascopus truei); and Northern red-legged frog (Rana aurora).
Likewise there are a small number of reptilian taxa within the ecoregion: Common garter snake (Thamnophis sirtalis); Western terrestrial garter snake (Thamnophis sirtalis); Northern alligator lizard (Elgaria coerulea); Western fence lizard (Sceloporus occidentalis); Northwestern garter snake (Thamnophis ordinoides); Sharp-tailed snake (Contia tenuis); Yellow-bellied racer (Coluber constrictor); and Western pond turtle (Clemmys marmorata).
There are numberous mammalian taxa present in the Puget lowland forests. A small sample of these are:Creeping vole (Microtus oregoni), Raccoon (Procyon lotor), Southern sea otter (Enhydra lutris), Mink (Mustela vison), Coyote (Canis latrans), Black-tailed deer (Odocoileus hemionus), Pallid bat (Antrozous pallidus), and Harbour seal (Phoca vitulina).
A rich assortment of bird species present in this ecoregion, including the Near Threatened Spotted owl (Strix occidentalis), Turkey vulture (Cathartes aura), Bald eagle (Haliaeetus leucocephalus), Blue grouse (Dendragapus obscurus), as well as a gamut of seabirds, numerous shorebirds and waterfowl.
Tailed frogs clear, cold streams of mountainous regions with step-pools, such that the slope is neither too shallow nor too steep. They inhabit a wide range of elevations from coastal to mountainous. Stream temperatures must remain cool even in summer months, as this species is known to have narrow temperature tolerances. Also, coarse substrates are favored for egg-laying and over-wintering events. As larvae do exhibit a long developmental period, stream habitats must be permanent features of the landscape. Juveniles and adults, however, further require the presence of a mature or old growth forest alongside their stream habitat. While they will not venture too far from the water, juveniles and adults will utilize riparian vegetation for food and refuge. This vegetation is also important to larvae, as it helps to control stream temperatures and prevent excessive sedimentation through bank stabilization.
Range elevation: 0 to 2557 m.
Habitat Regions: temperate ; terrestrial ; freshwater
Terrestrial Biomes: forest ; mountains
Aquatic Biomes: rivers and streams
Other Habitat Features: riparian
Habitat and Ecology
Central Pacific Coastal Forests Habitat
This taxon is found in the Central Pacific Coastal Forests ecoregion, as one of its North American ecoregions of occurrence. These mixed conifer rainforests stretch from stretch from southern Oregon in the USA to the northern tip of Vancouver Island, Canada. These forests are among the most productive in the world, characterized by large trees, substantial woody debris, luxuriant growths of mosses and lichens, and abundant ferns and herbs on the forest floor. The major forest complex consists of Douglas-fir (Pseudotsuga menziesii) and Western hemlock (Tsuga heterophylla), encompassing seral forests dominated by Douglas-fir and massive old-growth forests of Douglas-fir, Western hemlock, Western red cedar (Thuja plicata), and other species. These forests occur from sea level up to elevations of 700-1000 meters in the Coast Range and Olympic Mountains. Such forests occupy a gamut of environments with variable composition and structure and includes such other species as Grand fir (Abies grandis), Sitka spruce (Picea sitchensis), and Western white pine (Pinus monticola).
Characteristic mammalian fauna include Elk (Cervus elaphus), Black-tailed Deer (Odocoileus hemionus), Coyote (Canis latrans), Black Bear (Ursus americanus), Mink (Mustela vison), and Raccoon (Procyon lotor).
The following anuran species occur in the Central Pacific coastal forests: Coastal tailed frog (Ascaphus truei); Oregon spotted frog (Rana pretiosa VU); Northern red-legged frog (Rana pretiosa); Pacific chorus frog (Pseudacris regilla); Cascade frog (Rana cascadae NT), generally restricted to the Cascade Range from northern Washington to the California border; Foothill yellow-legged frog (Rana boylii) and the Western toad (Anaxyrus boreas NT). A newt found in the ecoregion is the Rough skinned newt (Taricha granulosa).
Salamanders within the ecoregion are: Del Norte salamander (Plethodon elongatus NT); Van Dyke's salamander (Plethodon vandykei); Western redback salamander (Plethodon vehiculum); Northwestern salamander (Ambystoma gracile); Olympic torrent salamander (Rhyacotriton olympicus VU), whose preferred habitat is along richly leafed stream edges; Long-toed salamander (Ambystoma macrodactylum), whose adults are always subterranean except during the breeding season; Dunn's salamander (Plethodon dunni), usually found in seeps and stream splash zones; Clouded salamander (Aneides ferreus NT), an aggressive insectivore; Monterey ensatina (Ensatina eschscholtzii), usually found in thermally insulated micro-habitats such as under logs and rocks; Pacific giant salamander (Dicamptodon tenebrosus), found in damp, dense forests near streams; and Cope's giant salamander (Dicamptodon copei), usually found in rapidly flowing waters on the Olympic Peninsula and Cascade Range.
There are a small number of reptilian taxa that are observed within this forested ecoregion, including: Pacific pond turtle (Emys marmorata); Common garter snake (Thamnophis sirtalis), an adaptable snake most often found near water; Northern alligator lizard (Elgaria coerulea); and the Western fence lizard.
Numerous avian species are found in the ecoregion, both resident and migratory. Example taxa occurring here are the Belted kingfisher (Megaceryle alcyon); Wild turkey (Meleagris gallopavo); and the White-headed woodpecker (Picoides albolarvatus) and the Trumpeter swan (Cygnus buccinator), the largest of the North American waterfowl.
Comments: Clear, cold swift-moving mountain streams with coarse substrates. Primarily in older forest sites; required microclimatic and microhabitat conditions are more common in older forests (Welsh 1990). Diller and Wallace (1999) reported that canopy cover, temperature, and forest age in managed forests were not significantly different between occupied and unoccupied stream reaches in northern California; however, this probably reflects past timber harvest patterns. May be found on land during wet weather near water in humid forests or in more open habitat. During dry weather stays on moist stream-banks. Lays eggs in long strings under stones in water.
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Animal Foods: insects; terrestrial non-insect arthropods; mollusks; zooplankton
Plant Foods: algae
Primary Diet: carnivore (Insectivore )
Comments: Larva feed mostly on diatoms. Adults eat a wide variety of insects and other invertebrates.
Tailed frog tadpoles can actually act as the dominant herbivore in some stream habitats. However, tailed frogs are restricted to aquatic lotic systems as a tadpole. As a juvenile or adult on the other hand, they may play an active part in both its aquatic and adjacent terrestrial ecosystem through interaction with its prey and predators.
Little is known regarding potential predators of tailed frogs, as observations regarding this subject of study are few in number. Of those accounts that exist, common garter snakes, shrews (Sorex) and western terrestrial garter snakes were observed consuming post-metamorphic tailed frogs. There are also accounts of hellgrammites (Megaloptera), larval Cope’s giant salamanders and Pacific giant salamanders consuming larval tailed frogs. Other predators include trout (Salmonidae), sculpins and dippers.
- common garter snakes (Thamnophis sirtalis)
- shrews (Sorex)
- western terrestrial garter snakes (Thamnophis elegans)
- hellgrammites (Megaloptera)
- Cope's giant salamanders (Dicamptodon copei)
- Pacific giant salamanders Dicamptodon tenebrosus
- trout (Salmonidae)
- dippers (Cinclus mexicanus)
- sculpins (Cottus confusus)
Anti-predator Adaptations: cryptic
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 81 to >300
Comments: Many extant occurrences distributed throughout the range. Washington has 436 unique sites, many of which will combine into a smaller number of distinct occurrences (K. Dvornich, pers. comm., 1997). Oregon has approximately 60 occurrences.
10,000 - 1,000,000 individuals
Comments: Total population size is unknown but likely exceeds 10,000. Common in suitable habitat.
Adult and subadult frogs usually are less commonly encountered than are larvae. For example, in California, Diller and Wallace (1999) found 693 A. truei larvae but only 32 metamorphosed individuals over four years in 54 of 72 randomly selected streams, though researchers have found higher densities in other areas. Diller and Wallace found 0.04-0.76 larvae per square meter (mean 0.24), whereas Hawkins et al. (1988) recorded mean densities of 0.58 to 4.40 larvae per square meter in three different classes of watersheds near Mt. St. Helens in Washington; two of the three sampled streams contained two larval cohorts.
Life History and Behavior
Communication through calls, as characteristic of most anurans, does not appear possible due to the absence of the tongue, vocal sacs, middle and external ear bones, and external eardrums which are critical to creating and perceiving sound. With acoustic communication lacking in tailed frogs, they are presumably reliant on visual and tactile cues to carry out courtship and mating activities. Still, more research is needed in this subject of study, as chemical cues may prove important to communication as well.
Communication Channels: visual ; tactile
Perception Channels: visual ; tactile
Comments: Adults most active April-October, depending on locality.
While most frogs and toads exhibit external fertilization, tailed frogs unique in that they have internal fertilization. Female tailed frogs purposefully attach their eggs to the bottom of big rocks or boulders found submerged in the stream. Hatching occurs about six weeks after deposition of the eggs. Tadpoles utilize their large yolk sac for nourishment throughout the winter months, after which development of a suctorial mouth allows them to prey upon other organisms. Following one to four years, metamorphosis takes place, producing juvenile tailed frogs that differ dramatically in appearance from their previous larval form. Metamorphosis can last up to 60 days. The age that juveniles reach sexual maturity varies geographically, with coastal populations maturing at 2 to 3 years old and montane populations maturing at 8 to 9 years old.
Development - Life Cycle: metamorphosis
With a maximum lifespan of at least fourteen years, and from 2 to 9 years required to attain sexual maturity, tailed frogs have one of the longer life histories known among anurans.
Status: captivity: 14 (high) years.
Lifespan, longevity, and ageing
Tailed frogs are unique among the anurans in exhibiting a combination of amplexus and copulation during courtship and mating. Courtship occurs at the onset of fall, between September and October, and is carried out in the water. During courtship, a male typically lunges or swims suddenly toward a female of the same species. Clasping the female’s body directly anterior to her pelvic region, the male may then perform either inguinal or ventral amplexus. Once in the proper position, copulation can follow, the male's erect “tail” inserted into the female’s cloaca. To press closer to the female during copulation, the male may repeatedly produce thrusts of his pelvic region, his “tail” still within the cloaca.
Mating System: polygynous
Tailed frog females have been shown to reproduce biennially, while males may mate annually. This behavior may vary geographically. Although courtship and mating occur in the fall, tailed frog females store the sperm and do not deposit eggs until June or July. When deposition finally takes places, a dual strand of 44 to 85 small-sized eggs is fixed to the base of a rock or boulder within the stream system. After approximately six weeks, hatchlings then appear. The tadpole or larval stage may last anywhere from one to four years, geographic location likely impacts the length. Coastal populations spend 1 to 3 years in the larval state, whereas montane or inland populations spend 3 to 4 years. Tailed frog tadpoles undergo metamorphosis, which includes absorbing their tails, developing an adult mouth, losing the suction mouth, and developing legs. A juvenile may not reach reproductive maturity until it is 2 to 8 years old, varying geographically.
Breeding interval: Tailed frog females breed biennially, while males may breed annually.
Breeding season: Tailed frogs breed from September through October (fertilization) and females lay eggs from June to July (oviposition).
Range number of offspring: 44 to 85.
Average time to hatching: 6 weeks.
Range age at sexual or reproductive maturity (female): 2.5 to 4 years.
Average age at sexual or reproductive maturity (female): 3 years.
Range age at sexual or reproductive maturity (male): 1.5 to 4 years.
Average age at sexual or reproductive maturity (male): 3 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous ; sperm-storing
There is little available information on parental care in tailed frogs.
Breeds May-October, mostly in fall. Fertilization is internal; male has a tail-like copulatory organ. Clutch size averages 44-75; eggs are laid in July, hatch in August-September. Larval period lasts 2-4 years in mountains and northern areas, 1 year in a few coastal Oregon populations (Bury and Adams 1999) and in lowland streams of California (Wallace and Diller 1998). May not breed until 7-8 years old or 6-8 years after metamorphosis (Nussbaum et al. 1983).
Molecular Biology and Genetics
Barcode data: Ascaphus truei
Below is the sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen.
Other sequences that do not yet meet barcode criteria may also be available.
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Download FASTA File
Statistics of barcoding coverage: Ascaphus truei
Public Records: 1
Specimens with Barcodes: 2
Species With Barcodes: 1
Ascaphus truei is ranked as a species of “Least Concern” on the IUCN Red List but are a “Species of Concern” for the Pacific region on the United States Fish and Wildlife Endangered Species List. The reason behind its status on either list is the fact that tailed frogs may be impacted by logging and construction activities. These practices can negatively alter tailed frogs' habitats by causing stream temperatures to rise and siltation to occur.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N3 - Vulnerable
Rounded National Status Rank: N4 - Apparently Secure
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
Reasons: Moderately widespread and locally common in the Pacific Northwest from British Columbia to northwestern California; may be detrimentally affected by habitat changes resulting from timber harvest (depends on surface geology and harvest practices), but exists in many young forests that have been harvested in the past.
Intrinsic Vulnerability: Highly to moderately vulnerable.
Environmental Specificity: Very narrow to narrow.
Global Short Term Trend: Decline of 10-30%
Comments: Probably declining, based on habitat trends; few population data are available.
Global Long Term Trend: Relatively stable to decline of 50%
Comments: Likely relatively stable in extent of occurrence, unknown degree of decline in population size, area of occurrence, and number/condition of occurrences.
Life History, Abundance, Activity, and Special Behaviors
Ascaphus is non-vocal. Its internal fertilization (an adaption to ensure fertilization in fast moving streams) is unique among frogs. Breeding season lasts from May through September. Eggs are deposited in strings under rocks in fast-moving streams. Tailed frogs are primarily aquatic; adults may emerge to forage on land in cool, wet conditions, especially at night. Larvae take between 1 to 4 years to metamorphose, depending on drainage (Bull and Carter 1996; Wallace and Diller 1998) . Juveniles are sexually mature in 7-8 years. Maximum average Ascaphusdensity per linear meter of stream was 0.162 larvae and 0.035 adults in western Oregon (Bull and Carter 1996). Nussbaum et al (1983) cite densities as high as 1 frog per meter of stream in eastern Washington.
Degree of Threat: Medium
Comments: Sensitive to logging and road building (Leonard et al. 1993). Logging and construction practices that increase water temperatures and siltation may have an adverse effect on tailed frog populations (Nussbaum et al. 1983, Welsh and Ollivier 1998). See also Bury and Corn (1988) and Corn and Bury (1989) for information on negative effects of timber harvest. Diller and Wallace (1999) emphasized that current timber harvest practices are not as detrimental as those used in the past. Despite negative effects of logging, this species frequently occurs in many young forests that have been harvested one or more times in the past. Sensitivity to timber harvest may depend on surface geology and harvest practices (Adams and Bury 2002, Welsh and Lind 2002).
Life History, Abundance, Activity, and Special Behaviors
Not federally listed, but a California Species of Special concern. Habitat modification due to timber harvesting may be a major cause of declines in Ascaphus. Bull and Carter (1996) found that the presence of a tree-lined buffer zone was significantly correlated with Tailed frog abundance, while overall logging level within the watershed showed only a non-significant trend. In British Columbia, conservation plans are difficult to implement, since Tailed Frogs (along with Pacific Giant Salamanders, Dicamptodon tenebrosus) avoid areas with predatory game fish; it is the riparian areas with those game fish that are protected (Orchard 1992).
Management Requirements: Maintenance of cool, forested, unsilted streams and stream corridors is a basic conservation need.
Global Protection: Several to many (4-40) occurrences appropriately protected and managed
Comments: Range includes several national parks and wilderness areas.
Relevance to Humans and Ecosystems
There are no known negative impacts of tailed frogs on humans.
Due to the sensitivity of tailed frogs to alterations of their habitat, this stream-dwelling species may serve as an indicator species in assessing ecosystem health.
Names and Taxonomy
Comments: Nielson et al. (2001) examined phylogeography of A. TRUEI using mtDNA data. Based on the results of this study and on previous allozyme and morphological data, they recommended that the coastal and inland segments of A. TRUEI be recognized as distinct species, A. TRUEI (coastal) and A. MONTANUS (inland). See also Ritland et al. (2000) for information on tailed frog phylogeography based on genetic variation.
Tailed frogs sometimes are placed in the family Leiopelmatidae. Stebbins (1985) placed them in the family Ascaphidae.